At the present time the strips are assembled manually in a process which is slow, calls for very competent operatives and does not guarantee absolutely regular geometry. The steps in this process are the following: an operative arranges a first set of strips parallel to each other in the grooves of an assembly jig. Once this operation, which may be compared to the setting up of the warp threads in the textile industry, has been completed, the operative arranges the strips which form a second set one by one, which may be compared to inserting the weft threads in woven material. To allow this assembling each of the strips of the first set has slots which co-act with complementary slots in the strips of the second set, providing lap-jointed fixing. Once all the strips are in place, a second assembly jig with identical grooves to those in the first is placed on the two sets of grille strips to maintain the intersection during the following stages for finishing the grille, which consist of setting in place four external framing strips, and the welding process.
Despite the fact that the operative is able to assess by his sense of touch the insertion force which he is exerting on the strips of the second set, local deformations may occur due especially to the fact that the strips in the first set are not held precisely in place while the second set is being inserted, and faults may result in the alignment of the slots receiving one and the same strip of the second set. Furthermore, when, as frequently happens, not all the strips in a grilles are identical, there is a very real danger of error in the choice of the strip to be placed in a given position.
The object of the present invention is to provide a process and assembly apparatus which are better adapted to practical requirements than those known previously, notably in that they eliminate, or at least attenuate to a large degree, the above-mentioned disadvantages. More particularly, the object of the invention is to provide a process and apparatus which make it possible to guarantee an exact, constant and precise geometry for the assembly.
To this end the invention proposes in particular a process for assembling grilles formed by two sets of similar strips, with the strips of one of the sets disposed orthogonally to the strips of the other set and comprising slots which co-act with complementary slots in the other set to form a lap-jointed assembly, this being a process according to which the first set is arranged in an assembly jig equipped with parallel slots for receiving the terminal sections of the strips of the first set, after which the second set of strips is inserted one by one. The assembly jig is displaced on fixed guide means to bring it into a position in which all the strips of the first set have their first slot disposed facing the insertion path for strips of the second set via a movable strip-insertion device, this path being orthogonal to the displacement direction of the assembly jig and defined by the fixed guide means; an appropriate strip from the second set is placed on the said movable device which is located in a retracted position; the movable device is advanced to cause it to penetrate between the strips of the first set and engage the strip of the second set at the bottom; the second set strip is released from the device; the latter is withdrawn and the sequence recommences for each strip of the second set.
According to another aspect of the invention, apparatus which enables this process to be carried out includes a sub-frame, a carriage which can be displaced on the sub-frame in a first direction, preferably vertically, a frame forming an assembly jig and attached to the carriage, a device which can be displaced on the frame perpendicular to the displacement direction of the carriage and parallel to the slots in the strips, this device comprising a table equipped with means for receiving and centering a second set strip and means allowing the frame to be held in successive predetermined positions in which the corresponding slots in the first set strips face the path of the second set strips carried by the movable device.